<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        body {
            background-color: #bbb;
        }

        #canvas {
            background-color: #fff;
        }
    </style>
</head>

<body>
    <canvas id="canvas" width="400" height="400"></canvas>
</body>
<script src="./utils.js"></script>
<script src="./ball.js"></script>
<script>
    window.onload = () => {
        var canvas = document.getElementById("canvas");
        var context = canvas.getContext("2d");
        var ball = new Ball();
        var speed = 1, angle = 45;

        ball.x = 50;
        ball.y = 100;

        (function drawFrame() {
            window.requestAnimationFrame(drawFrame, canvas);
            context.clearRect(0, 0, canvas.width, canvas.height);
            var vx = Math.cos(angle * Math.PI / 180) * speed;
            var vy = Math.sin(angle * Math.PI / 180) * speed;

            ball.x += vx;
            ball.y += vy;
            ball.draw(context);
        }())
    };
</script>

</html>